{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T16:15:57Z","timestamp":1753892157094,"version":"3.41.2"},"reference-count":21,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2023,10,10]],"date-time":"2023-10-10T00:00:00Z","timestamp":1696896000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Physiol."],"abstract":"<jats:p><jats:bold>Introduction:<\/jats:bold> This prospective cohort study assessed the effects of chronic hypoxaemia due to high-altitude residency on the cerebral tissue oxygenation (CTO) and cerebrovascular reactivity.<\/jats:p><jats:p><jats:bold>Methods:<\/jats:bold> Highlanders, born, raised, and currently living above 2,500\u00a0m, without cardiopulmonary disease, participated in a prospective cohort study from 2012 until 2017. The measurements were performed at 3,250\u00a0m. After 20\u00a0min of rest in supine position while breathing ambient air (FiO<jats:sub>2<\/jats:sub> 0.21) or oxygen (FiO<jats:sub>2<\/jats:sub> 1.0) in random order, guided hyperventilation followed under the corresponding gas mixture. Finger pulse oximetry (SpO<jats:sub>2<\/jats:sub>) and cerebral near-infrared spectroscopy assessing CTO and change in cerebral haemoglobin concentration (cHb), a surrogate of cerebral blood volume changes and cerebrovascular reactivity, were applied. Arterial blood gases were obtained during ambient air breathing.<\/jats:p><jats:p><jats:bold>Results:<\/jats:bold> Fifty three highlanders, aged 50 \u00b1 2\u00a0years, participated in 2017 and 2012. While breathing air in 2017 vs. 2012, <jats:italic>P<\/jats:italic>aO<jats:sub>2<\/jats:sub> was reduced, mean \u00b1 SE, 7.40 \u00b1 0.13 vs. 7.84 \u00b1 0.13\u00a0kPa; heart rate was increased 77 \u00b1 1 vs. 70 \u00b1 1\u00a0bpm (<jats:italic>p<\/jats:italic> &amp;lt; 0.05) but CTO remained unchanged, 67.2% \u00b1 0.7% vs. 67.4% \u00b1 0.7%. With oxygen, SpO<jats:sub>2<\/jats:sub> and CTO increased similarly in 2017 and 2012, by a mean (95% CI) of 8.3% (7.5\u20139.1) vs. 8.5% (7.7\u20139.3) in SpO<jats:sub>2<\/jats:sub>, and 5.5% (4.1\u20137.0) vs. 4.5% (3.0\u20136.0) in CTO, respectively. Hyperventilation resulted in less reduction of cHb in 2017 vs. 2012, mean difference (95% CI) in change with air 2.0 U\/L (0.3\u20133.6); with oxygen, 2.1 U\/L (0.5\u20133.7).<\/jats:p><jats:p><jats:bold>Conclusion:<\/jats:bold> Within 5\u00a0years, CTO in highlanders was preserved despite a decreased <jats:italic>P<\/jats:italic>aO<jats:sub>2<\/jats:sub>. As this was associated with a reduced response of cerebral blood volume to hypocapnia, adaptation of cerebrovascular reactivity might have occurred.<\/jats:p>","DOI":"10.3389\/fphys.2023.1160050","type":"journal-article","created":{"date-parts":[[2023,10,10]],"date-time":"2023-10-10T07:17:03Z","timestamp":1696922223000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Time course of cerebral oxygenation and cerebrovascular reactivity in Kyrgyz highlanders. A five-year prospective cohort study"],"prefix":"10.3389","volume":"14","author":[{"given":"Matthias C.","family":"Luyken","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paula","family":"Appenzeller","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Philipp M.","family":"Scheiwiller","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mona","family":"Lichtblau","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maamed","family":"Mademilov","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Aybermet","family":"Muratbekova","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ulan","family":"Sheraliev","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ainura","family":"Abdraeva","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nuriddin","family":"Marazhapov","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Talant M.","family":"Sooronbaev","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Silvia","family":"Ulrich","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Konrad E.","family":"Bloch","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michael","family":"Furian","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2023,10,10]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"201","DOI":"10.1016\/j.resp.2008.02.003","article-title":"Cardiorespiratory and cerebrovascular responses to hyperoxic and hypoxic rebreathing: effects of acclimatization to high altitude","volume":"161","author":"Ainslie","year":"2008","journal-title":"Respir. physiology Neurobiol."},{"key":"B2","doi-asserted-by":"publisher","first-page":"251","DOI":"10.1113\/expphysiol.2008.045575","article-title":"Regulation of cerebral blood flow in mammals during chronic hypoxia: A matter of balance","volume":"95","author":"Ainslie","year":"2010","journal-title":"Exp. 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